In a medium saucepan over medium heat, melt butter. Stir in the flour until combined. Stir in milk, egg yolks, cheese and salt. Continue to cook until the cheese has melted.

Pour the cheese mixture into a glass dish and chill overnight in the refrigerator.

Shape the croquette balls with your hands. Set aside.

In a small bowl beat together 1 egg and 1/4 cup milk. In another small bowl add the flour and in a third bowl add the breadcrumbs.

In a heavy bottomed pan, heat approximately 3 to 4" of oil over medium-high heat.

Roll the croquettes in the flour, then the egg and finally the crumbs to coat.

Deep fry in oil until golden, about 2 to 3 minutes, and drain on paper towels.

In a small saucepan, combine all ingredients for the sauce and bring to a boil. Reduce to a simmer and cook until the sauce has thickened. Serve with the croquettes as a dipping sauce.